The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A hybrid powertrain includes both an electric machine and an internal combustion engine. Power may be supplied by the electric machine and/or the internal combustion engine during operation of the engine. Use of the electric machine may increase efficiency of a vehicle having such a hybrid powertrain.
The drivetrain of a hybrid vehicle is configured in either a parallel configuration or in a series configuration. In a hybrid vehicle having a parallel drivetrain, the electric machine works in parallel (i.e., in combination) with the engine. The parallel configuration combines the power and range advantages of the engine with the efficiency and electrical regeneration capability of the electric machine.
In a hybrid vehicle having a series drivetrain, the engine drives a generator to produce electricity for the electric machine, and the electric machine drives a transaxle. The series configuration allows the electric machine to assume some of the power responsibilities of the engine, thereby permitting the use of a smaller and more efficient engine.
Some vehicles, including some hybrid vehicles, include a brake booster that reduces the brake pedal effort required to achieve a desired vehicle braking force. This vacuum is depleted as a driver modulates a brake pedal. Accordingly, sufficient vacuum may be required to maintain the braking assistance provided by the brake booster.